U.S. Pat. No. 5,523,400, issued Jun. 4, 1996 (Wei, et al) discloses certain cephalosporin antibiotics having a lactam moiety at the 3 position of the cephalosporin.
U.S. Pat. No. 4,409,214, issued Oct. 11, 1983 (Takaya, et al) discloses 7-acylamino-3-vinyl-cephalosporanic acid derivatives having antimicrobial activity.
Kamachi, et al, J. Antibiotics (December 1990) Vol. 43, pages 1564-1572 discloses the synthesis of 1-Acetoxyethyl 7-(Z)-2-(2-aminothiazol-4-yl)-2-hydroxyiminoacetamido!-3-(Z)-1-propenyl! -3-cephem-4-carboxylate by acylation of the cephem unit with an activated aminothiazole derivative in which the activating group is a benzothiazolyl ester.
European Patent Publication No. EP 620228, published Oct. 19, 1994 (Lucky, Ltd.) discloses thiophosphate derivatives of thia(dia)zole acetic acid for use in the preparation of .beta.-lactam antibiotics. In this case the cephem unit is acylated using an activated aminothiazole derivative in which the activating group is a mixed anhydride of thiophosphoric acid.
Other acyl groups which can be used to acylate .beta.-lactam antibiotics may be found in Cephalosporins and Penicillins, Flynn, ed, Academic Press (1972); Belgian Patent No. 866,038, published Oct. 17, 1978; Belgian Patent No. 867,994, published Dec. 11, 1978; and U.S. Pat. No. 3,971,778, issued Jul. 27, 1976.